Rotary engines

ABSTRACT

A housing defining a circular chamber. Two radial pistons with each piston comprising curved blocks, the pistons being journaled within the circular chamber of the housing for rotation and relative angular reciprocation. Working chambers defined by the pistons within the circular chamber. The rotation and angular reciprocation of the pistons is achieved by elliptical gears. Other forms of gear arrangements for this purpose are also described.

United State s Patent [e1 Scherrer 1 1 Nov. 6, 1973 1 ROTARY ENGINES [76] lnventor: William A. Scherrer, 6702 Alvina St., Bell Gardens, Calif. 90201 22 Filed: July 14,1969

211 App]. No.: 841,399

52 us. c1 123/8.47, 74/437, 418/36 51 Int. Cl. F02b 53/00, F016 1/00 58 Field 61 Search 123/11 A, 8.47; 91/60; 103/129; 230/144; 74 393, 437;-

[56] References Cited UNITED STATES PATENTS 1,482,628 2/1924 Bullington 123/11 A 2,108,385 2/1938 Murakami 123/11 A X 3,112,062 11/1963 Way 230/144 x FOREIGN PATENTS OR APPLlCATIONS 684,714 3/1930 France 123/11 A 1,209,648 9/1959 France 123/11 A 582,924 12/1946 Great Britain 123/1 1 642,255 7/1962 Italy 103/129 Primary ExaminerAllan D. Herrmann [57] ABSTRACT A housing defining a circular chamber. Two radial pistons with each piston comprising curved blocks, the pistons being iournaled within the circular chamber of the housing for rotation and relative angular reciprocation. Working chambers defined by the pistons within the circular chamber. The rotation and angular reciprocation of the pistons is achieved by elliptical gears. Other forms of gear arrangements for this purpose are also described.

13 Claims, 19 Drawing Figures ROTARY ENGINES BACKGROUND OF THE INVENTION.

1. FIELD OF THE INVENTION The present invention relates to rotary engines and more particularly to a rotary engine in which the pistons are rotated and angularly reciprocated within a housing.

2. DESCRIPTION OF THE PRIOR ART Rotary engines are known which use pistons that angularly reciprocate relative to one another, while rotating. A main drawback to such engines has often been that their piston driving mechanisms have been difficult to balance. The piston drive mechanism for such engines often use planetary gears and a train of linkage, including at least one connecting rod which rotates with the planet carrier, and cranks attached to the planet gears to operate the connecting rods. The rods oscillate about secondary axes peripheral to the axis of the planet carrier. The oscillation of linkage, radial centrobaric oscillation, causes irregular inertial forces and makes the mechanisms very difficult to balance.

Another major drawback to planetary piston drive mechanisms used in these engines is'their complexity. And a third drawback to the piston drive mechanisms is that the acceleration imparted to the pistons is much greater at one portion of a cycle than it is elsewhere in SUMMARY OF THE INVENTION In essence my engine is a rotary engine in which the pistons undergo rotation and angular reciprocation. In order to obviate the above mentioned disadvantages of hitherto existing machines my engine uses a nonplanetary arrangement of elliptical gears (and more generally gears with rounded lobes) to regulate the pistons. Having no planet carrier, my engine is simplified. There. is no linkage in my engine to cause irregular inertial forces and vibration. .The elliptical gears rotate about stable axes and are symmetrical and: consequently they'have good balance characteristics.

In the first embodiment only four elliptical gears are used, two of which rotate in unison, coupled by a power shaft, and the other two gears rotate coupled to two individual radial pistons. The gears coupled to the pistons rotate with varying speed whereby the pistons angularly reciprocate. Y

My engine takes advantage of the action of these gears by incorporating pistons which are non-complex and well sealing, these pistons comprising curved blocks and with the curved blocks sealed on all sides. The preferable arrangement is with two pistons, each piston having two diametrically opposed curved blocks. The pistons define four working chambers, which in an internal combustion engine act as combustion chambers. This arrangement is without complexity. Also in the'preferred arrangement the engine breathes through an inlet and an outlet advantageously arranged, and it has no valves.

It is therefore a principle object of my invention to provide an improved rotary engine of a type in which the pistonsrotate and angularly reciprocate within a circular chamber of a housing.

It is another object of my invention to provide an improved internal combustion engine which is compact, has improved sealing and improved beeathing, and incorporates mechanism which allowsthe engine to operate at high speeds.

It is still another object of my invention to provide an internal combustion engine which is simplified over the above mentioned hitherto existing machines.

These and other objects of my invention will be apparent from the following description and the following drawings in which:

BRIEF DESCRIPTIONS OF DRAWINGS FIG. I is a sectional view taken along the width of the engine;

FIG. 2 is a sectional view of the engine taken through the housing along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 33 of FIG. 1 and showing details of the piston drive mechanism;

FIG. 4,5,6 are views of elliptical gears in a rotational sequence;

FIG.- 7,8,9,l0 are diagrammatical views of the housing and pistons, depicting a rotational sequence.

FIG. l1,l2,13,l4l,l5,1l6,17,18 are views of modifications of the piston drive mechanism; and

FIG. 19 is a view of a modification of the pistons of the engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, a housing 3 defines a cylindrical chambers and has a removable front side cover plate 2. The generatrix of the cylindrical chamber is a rectangle with four straight sides. The housing 3 also has a back plate 9 that provides a partition between the cylindrical chamber 8 and the piston drive mechanism which is contained in its own housing 5. The housing 3 may be water cooled in a manner well known to those skilled in the art.

A shaft 11 extends from the piston drive mechanism housing 5 into and through the cylindrical chamber 8. Shaft 11 is joumaled in an outboard bearing 13 which is seated in a recess at the outside end of the front plate 2. The shaft 1 1 is joumaled at its other end in a bearing 15 which is seated in a recess at the inside of the piston drive mechanism housing 5. The recess for the outboard bearing 13 is provided by an annular shoulder 14 formed in the front plate 2 adjacent to shaft 11. The

shaft 11 is stepped and has a first large diameter portion 17 that abuts the bearing 13, and a second larger boss portion 19 that abuts the inside of the shoulder 14. The boss portion 19 acts as a hub to a piston.

Telescoped over the inner end of the shaft 1 1 is a hollow second drive shaft 22 which extends partially into the chamber 8 and partially into the enclosure of the housing 5. The drive shaft 22 is journaled at its outer end on a bearing 29 through which the drive shaft 11 axially extends. The bearing 29 provides for relative rotation of shaft Ill and shaft 22. The shaft 22 is also stepped and has a large diameter boss portion 24 equal to and side by side adjacent the boss portion 19 of shaft 11 the boss portion 24 also acts as a hub to a piston. The shaft 22 is journaled at its inner end in a bearing 35 which abuts the large diameter portion 24 of the shaft 22 and is seated in the back plate 9 of the housing 3.

Studs 36 serve to rigidly secure to the boss portion 19 of shaft 11, a pair of segmental-shaped curved blocks 42 at remote diametrically opposed positions with the arcuate inner portions of the curved blocks 42 against the hub 19 of the shaft. These curved blocks 42 lie along the diameter of the cylindrical chamber 8, and the arcuate outer ends of the curved blocks just clear the cylindrical wall 16 of the chamber 8. The pair of curved blocks 42 together make up one radial piston which is in effect journaled within the cylindrical chamber 8 for rotation about the cylindrical chambers axis.

The large diameter portion 24 of shaft 22 has attached to it a second pair of remote diametrically opposed curved blocks 52. These curved blocks 52 are rigidly secured to the shaft 22 by means of studs 48. This pair of curved blocks 52 make up another piston which is journaled within the chamber 8 for rotation about the axis thereof.

Thrust washers 21 and 31 at the ends of the large diameter portions 19 and 24 of the drive shafts provide continuous working clearances between the radial pistons 42 and 52 and the front plate 2 and back plate 9, but prevent the radial pistons 42 and 52 from ever touching these plates. This allows the pistons to rotate with practically no friction, yet the clearance can be very small so that the pistons have good sealing properties. Piston sealing is aided by the configuration of the pistons; each curved block of a piston is arcuate, bounded by radial faces, and covers a substantial angular spread which helps prevent the escape of a high pressure gas.

For still better sealing, the pistons 42 and 52 are each fitted with sealing strips 10, in radial grooves along the sides and in axial grooves along the arcuate outer ends and the arcuate inner ends of the curved blocks. Means are therefore provided to additionally seal all sides of the curved blocks where a high pressure gas might escape.

From the description so far it is evident that there are two low friction, sealed pistons within the cylindrical chamber 8 of the housing, with each piston comprising a pair of diametrically opposed curved blocks. Both pistons are rotatable about the axis of the cylindrical chamber 8. Each of the pistons is connected to a separate drive shaft 11 and 22 which are rotatable relative to one another, and consequently the pistons may move through a limited angle relative to one another about the same axis. Therefore the pistons are rotatable and may undergo relative angular reciprocation within the cylindrical chamber 8. As used throughout this disclosure one angular reciprocation will mean the relative movement between the pistons when a chamber defined between the pistons goes from fully decreased volume to fully enlarged volume or else goes from fully enlarged volume to fully decreased volume.

Each piston, except for small clearances, extends the full depth of the cylindrical chamber 8, filling in a part of that cylindrical chamber. Together with the large portions 24 and 19 of the drive shafts, the pistons 42 and 52 define within the cylindrical chamber 8, smaller sectoral working chambers, A,B,C,D. To feed a fuel and air mixture to the working chambers there is provided an inlet 30 at the top portion of the back plate 9. To allow exhaustgases to be expelled from the working chambers there is provided an outlet 44 in the top portion of the front plate 2. The inlet and outlet each cover approximately relative to the axis of the cylindrical chamber 8 and communicate with the working chambers throughout the intake and exhaust strokes, respectively. The center of the outlet is angularly offset approximately 90 counter-clockwise from the center of the inlet. (FIG. 2) By having the inlet and the outlet in the back plate 9 and the front plate 2, respectively, a lubricant used in the engine is not thrown through the outlet by centrifugal force. This arrangement also allows very adequate breathing because the flow of gases is from side to side.

The inlet 30 and the outlet 44 overlap to a small extent near the top of the housing 3. This overlapping of the inlet and outlet provides for a momentary cross ventilation of each working chamber which removes from each chamber residual burnt gas and replaces it with fuel-air. The cross ventilation and good breathing afforded by the arrangement of the inlet and the outlet gives the engine increased power.

The operation of my engine is as follows, reference being made to FIGS. 7 through 10. Four working chambers are defined by the pistons and are designated A,B,C,D. These working chambers successively enlarge and decrease in volume upon relative angular reciprocation of the pistons 42 and 52 and consequent approach and departure of the respective curved blocks. The pistons angularly reciprocate four times as they revolve once, so that each of the working chambers enlarges and decreases in volume two times in a revolution. Operating this way, each chamber, one after another in the order A,B,C,D will rotate to a position opposite the inlet regulated to enlarge and draw in a charge of fuel and air. Each chamber will rotate to a position opposite the outlet 44 regulated to decrease and expel a charge of burnt gas. The working chambers are thus regulated to perform the appropriate strokes opposite to the inlet and the outlet.

The sequence depicted in FIGS. 7,8,9 and 10 shows all four working chambers undergoing strokes simultaneously. In FIG. 7 chamber A is opposite the inlet 30 and is nearly empty, chamber B is opposite the outlet 44 and contains a previously burned'charge, chamber C is opposite the electrical spark plug 61 with a compressed charge of fuel and air, chamber D is enclosed and contains a charge of fuel and air. The spark plug 61 ignites the charge in chamber C causing chamber C to enlarge and the pistons toangularly reciprocate, whereby chamber A enlarges and draws in a charge of fuel and air through the inlet 30, chamber B decreases and expels its burned charge through the outlet 44, chamber D decreases and compresses its charge of fuel and air (FIG. 8). When the working chambers have completed these strokes they will have rotated 90. Consequently each chamber now succeeds the previous position of the chamber clockwise to it and will be regulated to perform the same stroke. Effectively, the chambers have shifted position and in FIG. 9 chamber A is now enclosed, chamber B is opposite the inlet,'C is opposite the outlet, D is opposite the spark plug. Upon ignition of the charge of fuel and air in chamber D it is enlarged; the pistons angularly reciprocate, whereby chamber A decreases and compresses its charge of fuel and air, chamber B enlarges and draws in a fresh charge of fuel and air, chamber C decreases and expels its charge of burned gas. When these strokes are completed the chambers will have rotated another 90. At this point the chambers have shifted again and now (FIGQ chamber A is opposite the spark plug, B is enclosed, C is opposite the inlet, D is opposite the outlet. With the next angular reciprocation of the pistons chamber A undergoes combustion, B compression, C intake, and D the exhaust strokes. After completing these strokes and another 90 rotation the chambers shift positions again. Then chamber A will be opposite the outlet, B will be opposite the spark plug, C will be enclosed, and D will be opposite the inlet. Consequently with the nextpiston angular reciprocation chamber A will undergo the exhaust stroke, chamber B the combustion, chamber C the compression, and chamber D the intake. After the chambers have completed these strokes they will have rotated a total of 360 and will be back to their original positions as in FIG. 7. I

Each working chamber. has undergone a combustion stroke in the revolution and consequently there are four combustions in the revolution. Also each individual chamber has completed four strokes.

Referring now to the drawings up to FIG. 6 the piston drive mechanism of my engine will be described. The piston'dn've mechanism is the-means to regulate the rotation and relative'angular reciprocation of the pistons. In the first embodiment of the piston drive mechanism only four identical, toothed second order elliptical gears 72,75,82 and 85 are used to move the pistons. (For more information on elliptical gears and the construction of second "orderlelliptical gears I'make reference to the book titled Mechanisms, Linkages, and Mechanical Controls, edited by Nicholas Chironis and published by McGraw-I-Iill Book Co.).

The first gear 72 is a second order elliptical gears which is rotatable about its geometrical center and in effect is characterized by two diametrically opposed rounded lobes. The gear 72 is rigidly secured to the end of the drive shaft 22, so that the drive shaft. 22. is rotatable with gear 72. This drive shaft 22 serves also to couple the gear 72 to the piston 52 for rotation therewith about the axis of the cylindrical chamber.

Arpower shaft 80 is rotatable about an axis parallel to the axis of the cylindrical chamber and fixed relative to the housingfl. Thev power shaft is the means by which power and torque are transmittedfrom the engine. The

power shaft 80 is joumaled at its inner end in a bearing .83 seated in the back plate 9 and is journaled at its outer end in a bearing 88 seated in the housing 5. Rigidly secured tothe power shaft 80 for rotation therewith as a unit about its axis are the second gear 82 and the third gear 85, both of which are identical to gear 72. These gears 82 and 85 are secured to the power shaft 80 out of phase with one another. By out of phase I mean the gears are angularly offseton the power shaft so that the maximum radii of one gear bisect the angles formed between the maximum radii of the other gear. In this case the maximum radii of the two gears 82 and 85 are angularly offset 90. 7

Gear 82 is adjacent to gear 72 and is engaged with gear 72 by direct mesh of teeth. As a second order ellipticalgear, gear 82 isconjugate to the second order elliptical gear 72. By conjugate I mean having a gear shape which is matched to the shapeof 'an adjacent gear whereby the conjugate gear and the adjacent gear will always stay in contact when rotated about their respective axes. Gear 72 and its conjugate gear 82 canalways stay in mesh though their contacting radii change with rotation.

A fourth gear 75 is also a toothed second order elliptical' gear and is identical to gear 72. Gear 75 is rigidly secured to the end of the drive shaft 11, so that the drive shaft 1 l is rotatable with gear 75. This drive shaft 11 serves also to couple'gear 75 to the piston 42 for rotation therewith about the axis of the cylindrical chamber 8. The third gear 85 is adjacent to the gear 75 and engaged with it by direct mesh, and gear 85 is' conjugate to gear 75.

All of the gears 72,75,82 and 85 and the shafts to which they are secured rotate about stable axes. The means of engagement between the gears are solely the teeth of the gears which, being integral to the gears, rotate with them. There is no radial centrobari'c oscillation of either the gears or the means of engagement of the gears. By radial centrobaric oscillation is meant movement of center of mass of a body in and away from an axis of rotation and this movement is found in linkage or a connecting rod operated-by an eccentric.

Since the gears are symmetrical and rotate about stable Y axes they have good balance. And the gears may be, if wished, easily balanced to precision for speeds far exceeding the operational speeds of my engine by meansof drilling, shaving or other methods well known to I those skilled in the art. I-Ience my engine is not limited in speed by imbalance in the piston drive mechanism. All other major parts of the engine, including the pistons, have good balance characteristics and the engine is able to attain high speeds without vibration.

In operation, at any particular engine speed gear 82 rotates with substantially constant speed. To help insure smooth and constant speed rotation of gear 82, a flywheel 90 is secured to the end of the power shaft for rotation therewith. The flywheel, incidentally, serves also as a means to couple the engine to devices to be driven'by the engine. However, the gear 72 varies in speed due to the continuously changing ratio between the two engaged gears. Gear 72 rotates alternately fast and slow.

This action of the gear 72 is best shown in the FIGS. 4 to 6 depicting a sequence of rotation of gear 82 and gear 72. In FIG. 4 a large radius of the lobe m of gear 82 is opposite to a minimum radius region of gear 72 and the respective ratio of radii between the gears is large. At this high ratio gear 72 is in its high speed position. After a rotation of gear 72 through approximately a minimum radius region of gear 82 is opposite to a large radius region of gear 72 and the ratio of radii is high. Gear 72 is now in a slow speed position (FIG. 5). After another 90 rotation of gear 72 a lobe n of gear 82 is opposite to a minimum radius region of gear 72, and gear 72 is in a high speed position a'gain (FIG. 6). The sequence corresponding to rotation sees the gear 72 rotate fast-slow-fast in a cycle, in response to the rotation of gear 82. "t

The gear 72 accelerates as fast as it decelerates as a result of gear 72 being symmetrical, with a contacting radius that decreases as fast as it increases This is an advantage in my invention for with no extraordinarily large acceleration of the speed varying gears, inertial forces generated by the pistons are minimized.

When gear 72 rotates through another 180 the change in its contacting radius is from small, corresponding to its high speed position, to large radius slow speed position, to small radius high speed position. The cycle of speed-slow-speed is repeated. Hence gear 72 will complete a full revolution by undergoing two cycles of speed variation. Piston 52, coupled to gear 72, duplicates this motion and also undergoes two cycles of speed variation per revolution.

Since the power shaft 80 serves as a means to couple gear 82 to gear 85, these gears 82 and 85 rotate in unison about the same axis and gear 85 also rotates at constant speed for any particular engine speed. Between gears 85 and 75 the relationship is the same as that relationship just described between gears 82 and 72. Gear 75 engaged with gear 85 therefore, completes a revolution by undergoing two cycles of speed variation. Piston 42 coupled to gear 75 also undergoes two cycles of speed variation per revolution.

All four gears co-operate to cause the pistons to angularly reciprocate when the power shaft 80 and gears 82 and 85 rotate at a constant speed, and the gears 72 and 75 each speed and slow two times per revolution. The out of phase relationship of gears 82 and 85 insures that gear 72 speeds while gear 75 slows and that gear 75 speeds while gear 72 slows. The pistons too will speed and slow contrarily, and consequently the pistons angularly reciprocate relative to one another four times in a revolution.

The gear 72, though speed varying, rotates with the average speed of gear 82 as a consequence of the numbers of lobes of gears 72 and 82 being the same. Likewise gear 75 rotates with the average speed of gear 85. Since gear 85 and gear 82 rotate in unison it requires that gear 72 rotates with the same average speed as gear 75 though both gear 72 and gear 75 are speed varying and they speed and slow contrarily. The strokes of the engine are regulated to commence with the major radii of the second gear 45 angularly displaced from a hypothetical line perpendicular to the axis of rotation of the second and third gears and connecting the axis of rotation of the second and third gears to the axis of rotation of the first and fourth gears and with the major radii of the third gear also 45 angularly displaced from such a line. By this arrangement the pistons will not interfere.

My invention may admit of many modifications. While in the first embodiment the gears 82 and 85 secured to the power shaft were two lobed gears, other means to rotate gear 72 and gear 75 could be used. For example, a toothed basic elliptical gear whose pitch line is in the shape of a true ellipse and which has in effect one rounded lobe, will be conjugate to and will mesh with a second order elliptical gear. FIG. 11 depicts by pitch lines the basic elliptical gear 112 engaged with the second order elliptical gear 72. Because gear 112 has only one lobe it will rotate twice as fast as the average speed of gear 72. Gear 72, none the less, will still rotate with two cycles of speed variation per its revolution. Gear 115 is identical to gear 112 and is engaged with gear 75..An operational piston drive mechanism using basic elliptical gears rigidly secured out of phase with one another to power shaft P-in this case the maximum radii of the gears are angularly offset l80is shown in FIG. 11. This embodiment has its own particular advantages, namely that these basic elliptical gears cause greater speed variation and angular reciprocation in second order elliptical gears, and consequently second order elliptical gears that are of less curvature, as it turns out greater strength, can be used. Also the operational speed of the power shaft by this arrangement will be closely matched to the operational speed of a conventional piston engine, and the engine could be readily used for the same applications without the employment of additional reduction gears.

Another means to rotate the gears 72 and 75 is by gears having three rounded lobes, such as third order elliptical gears. All the gears hereinafter mentioned in the description of this disclosure are toothed and are depicted by pitchline. Third order elliptical gears will be conjugate to second order elliptical gears. FIG. 12 depicts a third order elliptical gear 132 in mesh with gear 72. Gear 72 will still rotate with two cycles per revolution but gear 132 will rotate with two-thirds the average speed of gear 72. Gear 135 is identical to gear 132 and gear 135 is meshed with gear 75. An operational piston drive mechanism using third order elliptical gears 135 and 132 rigidly secured out of phase with one another to a power shaft P, is depicted in the FIG. 12. A particular advantage of this embodiment is that the cycles of speed variation of the gears 72 and 75 are sinusoidal, causing minimum variation of piston acceleration which minimizes inertial forces generated by the pistons. Third order elliptical gears of the arrangement also wear better because they alternately present difierent lobes to be opposite the minimum radius regions of the second order elliptical gears.

Although I have chosen an arrangement of all second order elliptical gears for the first embodiment because it is simpler to make, toothed external gears of any number N of rounded lobes will be conjugate to and will mesh with the second order elliptical gears 72 and 75, and will cause the gears 72 and 75 to rotate with two cycles of speed variation per revolution. It is only required in my invention that the gears meshing with gears 72 and 75 be conjugate to those gears respectively, and I will put no restriction on the number of lobes of the gears secured to the power shaft. Several modifications of the piston drive mechanism can be made, then, by using two gears having the same number N of lobes, with these twov gears secured substantially out of phase with one another to the power shaft. In all such modifications the gears, such as gear 72 and gear 75, coupled to the pistons remain as two lobed gears.

Still another means to rotate the gears 72 and 75 is multilobed internal gears such as the gears 142 and 145 of FIG. 14. The FIG. 14 depicts a piston drive mechanism using a multi-lobed internal gear 142 which is engaged with gear 72, and an identical multilobed internal gear 145 engaged with the gear 75. The gears 142 and 145 are rotatable about the same axis which is parallel to the axis of the cylindrical chamber, and is fixed relative to the housing. Gears 145 and 142 are coupled for rotation in unison. With these multi-lobed internal gears, too, the gear 142 engaging with gear 72, and the gear 145 engaging with gear 75, have the same number N, of lobes, and are secured out of phase with one another. Still, the gears 72 and 75 will rotate with two cycles of speed variation per revolution with this arrangement. Modifications using internal gears having a number N, of internal lobes other than what is depicted in FIG. 14 would also be suitable; therefore I will put no restriction on the number of lobes N, of the internal gears as long as the number of lobes N, is the same for both gears that are engaged with gear 72 and gear 75 respectively. The advantage of using internal gears is that the gears which are engaged have nearly the same concavity whereby more teeth on the gears take up strain. ii r Still another modification of the piston drive mechanism using internal gears is one where the internal gears are coupled to the pistons (FIG. 16). Internally oval gears 172 and 175 whose teeth lie along their inscribed curves, are identical. Gear 172 is coupled to one of the pistons to rotate about the axis of the cylindrical chamber therewith, and gear 175 is coupled to the other piston to rotate about the axis of the cylindrical chamber therewith. Gears 182 and 185 are one lobed gears secured out of phase with one another and are coupled preferrably by a power shaft P for rotation in unison about an axis which is fixed relative to the housing and substantially parallel to the axis of the cylindrical chamber. Gears 1'82 and 185 rotate at twice theaverage speed of gears 172 and 175; and gear 182 is meshed with. gear 172 and is conjugate to gear 172, and gear 185 is meshed with gear 175 and is conjugate to gear 175. Gears 172 and 175 rotate with two cycles of speed variation per revolution. The gears cooperate to cause gear 172 to rotate successively faster and slower than gear 175 whereby the pistons angularly reciprocate four times in a revolution. This modification has the advantages that many teeth of the meshing gears take up the strain, and the operational speed of the power shaft P is near to that of conventional engines.

Furthermore, while the first embodiment of the piston.drive mechanism causes both pistons to undergo the same degree of speed variation, it is not strictly necessary to haveboth pistons undergo equal speed variation. Thus one pair of meshing gears may be different than-the other pair of meshing gears. A very simplified piston drive mechanism would be that which isshown in FIG. 13 in which a circular gear 77 replaces the elliptical gear 75 and a circular gear 87 replaces the gear 85. With this mechanism only one piston will undergo speed variation and contribute to the relative angular reciprocation of the pistons, because the other piston coupled to circular gear 77 rotates at substantially constant speed. The average speed of the pistons will be the same because the gear ratio of the circular gears is 1:1 so that the circular gears rotate at the same speed, and the gears 82 and 77 rotate in unison, and as aforementioned the average speed of gear 72 is equal to the speed of gear 82. Thus by the circular gears ratio of 1:1 and by gear 82 and gear 72 having the same number of lobes it is insured that the pistons will rotate at the same average speed and will not interfere. This modification would be easier to construct than any other mentioned, and it might find use in inexpensive engines such as for power mowers or outboard motors.

The embodiment shown in FIG. 13 is but one form of the piston drive mechanisms which use a pair of engaged circular gears and a pair of engaged lobed gears. In similar arrangements, the gears secured to the power shaft and engaged with gear 72 may have any whole number N of lobes. One of the circular gears will be rigidly secured to the power shaft for rotation therewith and one of the gears will be rigidly secured to the drive shaft 11 and the gear ratio of these gears will be N22 respectively. By this gear ratio of N2 of the circular; gears the pistons will rotate with the same average speed and will not interfere. Therefore I will not restrict the number N of lobes of the gear secured to the' power shaft in such mechanisms-In all such mechanisms the piston coupled to a circular gear rotates at constant speed for a particular engine speed, the other piston coupled to the gear 72 will rotate with two cycles of speed variation per revolution.

Also a circular internal gear 148 can replace the multi-lobed internal gear 145, and a circular gear 78 can replace the gear 75 (FIG. 15) to provide another embodiment. The gear ratio of gear 148 to gear 78 is N52 so that the pistons will rotate with the same average speed. This embodiment of the piston drive mechanism is shown in FIG. 15.

As still another modification, an internal circular gear 178 can replace the internal oval gear 175 and a circular gear 188 can replace the one lobed gear 185. The gear ratio of gear 178 to gear 188 is 2:1. This embodiment isshown on FIG. 17.

There may be still other modifications to the piston drive mechanism. The means of engagement between the gears 82 and 72 and the means of engagement between gear 85 and 75 may be indirect. There may, for example, be intermediate gears such as the two lobed elliptical gear 152 between gear 82' and gear 72, and the two lobed elliptical gear 155 between gear 82 and 72, as shown in FIG. 18. The intermediate gears 152 and 155 are useful (1) as a means to provide rotation and angular reciprocation intwo auxilliary members such as radial pistons in a pump (2) for harmonic balance; if rotatable masses such as flywheels were coupled to the intermediate gears, kinetic energy will be conserved in those flywheels and consequently the power shaft rotates without impulses (3) as a means to rotate the pistons in another engine.

As another modification, an adjusting means to adjust gear 82 relative in angular position to gear 85 could be incorporated to alter the compression ratios of the working chambers, A,B,C,D.

It is furthermore to be understood that all gears so far mentioned as being of a certain elliptical configuration do nothave to be strictly the shape mentioned as described mathematically. Slight alterations from the mathematically defined curves can be allowed, such as, for example, having one lobe slightly narrower than an other lobe on the same gear, or by having the lobes be displaced through a small angle. Also the axis of the power shaft does not have to be strictly parallel to the axis of the cylindrical chamber; the teeth of the gears may be modified with a bevel relative to the axis of rotation of the gears, or the teeth of the gears may be cut along'the lines of elliptical helixes.

Furthermore the housing and the pistons of my engine may also .be modified. The blocks which are curved along their arcuate inner ends and arcuate outer ends may also be curved along their sides, with the circular chamber being torroidal instead of cylindrical in configuration.

It is apparent also that the curved blocks may be of different angular spreads. For example, referring to FIG. 19, each of the curved blocks 43 covers less angular spread than each of the other curved blocks of the other piston 53. This arrangement, shown in FIG. 19,

is advantageouslyfused with a piston drive mechanism which causes one piston to rotate with constant speed and the other piston to rotate with varying speed. The piston 43, having the lesser angular spread, will rotate with speed variation and it gains the advantage of being of less weight than the piston 53 that rotates with substantially constant speed. Also with this arrangement the working chambers will enlarge and decrease at exactly the same positions relative to the cylindrical chamber 7 and housing 4, so that only one spark plug, one inlet and one outlet are required, and all working chambers breathe equally.

It is furthermore to be understood that while a fuel and air mixture was mentioned for use in my engine, other combustible fluids such as, for example, a hydrogen-oxygen mixture could be used.

The engine may also be easily adapted to work with steam or other heated gases by duplicating the inlet and the outlet at the bottom portion of the housing.

And it is also to be understood that some of the piston drive mechanisms described may be made small enough to be placed centrally within the pistons, the power shaft extending through the central portion of the engine and the speed varying gears coupled directly to the pistons.

Beyond these changes my invention may admit of many further modifications that fall within the spirit of the disclosure.

I claim: 1 I

1. In a rotary engine, a housing defining a circular chamber, two radial pistons joumaled on the axis of said circular chamber for rotation and relative angular reciprocation, each piston comprising at least one curved segmental block, at least two of said segmental blocks being arcuate, said pistons and said circular chamber defining at least two working chambers that successively enlarge and decrease in volume upon relative angular reciprocation of said pistons, and means to regulate the rotation and relative'angular reciprocation of said pistons, said means comprising,

A first gear characterized by two rounded lobes and coupled to one of said pistons for rotation therewith; a second gear characterized by N rounded lobes, N 1,3 or any interger number greater than 3, said second gear engaged with said first gear; a third gear characterized by having the same number N of rounded lobes as said second gear, saidthird gear coupled to said second gear for rotation therewith about an axis stable relative to said housing; a fourth gear characterized by two rounded lobes and engaged with said third gear and coupled to the other of said pistons for rotation therewith.

2. An invention according to claim 1, with each piston comprising two remote curved arcuate segmental blocks, with each curved block generally triangular and bounded by generally radial faces, means to rigidly interconnect the curved blocks of one said piston, means to rigidly interconnect the curved blocks of the other said piston, each of the said pistons having central bosses extending part way into said circular chamber, the two pistons interfitting with one another within said housing with the said central bosses side by side adjacent to one another, said, pistons and said circular chamber defining at least four working chambers that successively enlarge and decrease in volume upon relative angular reciprocation of said pistons.

3. An invention accordingto claim 1 wherein said circular chamber is the generatrix of a body having all sides straight.

4. An invention according to claim 3, said circular chamber being cylindrical, each piston comprising at least two said segmental blocks, and wherein said pistons and said circular chamber define at least four working chambers that successively enlarge and decrease in volume upon relative angular reciprocation of said pistons.

5. An invention according to claim 1, with all the gears of said engine being disposed on one side of said housing.

6. An invention according to' claim 5, with means to couple said fourth gear to said piston comprising a drive shaft, the means to couple said first gear to the other said piston including a member circumvented over the said drive shaft.

7. In a rotary engine, a housing defining a generally circular chamber, at least two pistons joumaled on the axis of said circular chamber for rotation and relative angular reciprocation, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising,

A first gear characterized by two rounded lobes and coupled to one of said pistons for rotation therewith; a second gear characterized by one one rounded lobe and engaged with said first gear; a third gear characterized by one rounded lobe, said second gear coupled to said third gear; a fourth gear characterized by two rounded lobes and engaged with said third gear and coupled to the other said piston for rotation therewith.

8. In a rotary engine, a housing defining a generally circular chamber, at least two pistons joumaled on the axis of said circular chamber for rotation and angular reciprocation of at least one piston relative to another, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising,

A first gear characterized by two rounded lobes and coupled to one of said pistons for rotation therewith; a second gear characterized by having N rounded lobes, N 1,3 or any integer number greater than 3, said second gear engaged with said first gear; a third gear, substantially circular, and coupled to said second gear; a fourth gear, substantially circular, and coupled to another of said pistons for rotation therewith and engaged with said third gear, the ratio of said third gear to said fourth gear being N:2.

9. In a rotary engine, a housing defining a generally circular chamber, at least two pistons joumaled on the axis of said circular chamber for rotation and angular reciprocation of at least one piston relative to another, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising,

A first toothed gear characterized by having at least one rounded lobe, said first gear coupled to one of said pistons for rotation therewith; a second lobate toothed gear, said second gear being an internal gear, said second gear engaged with said first gear; a third gear, said third gear coupled to said second gear; a fourth gear coupled to another of said pistons for rotation therewith; means for direct or indirect engagement of said third gear with said fourth gear.

10. 'An invention according to claim 9 wherein said first gear is characterized by two rounded lobes.

11. In a rotary engine, a housing defining a circular chamber, two radial pistons, each piston comprising at least one curved block, with said radial pistons journaled within said circular chamber on the axis thereof for rotation and relative angular reciprocation about said axis, said radial pistons substantially defining within said circular chamber at least one working chamber that successively enlarges and decreases in volume upon relative angular reciprocation of said pistons and consequent approach and departure of said curved blocks, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising,

A first toothed gear having at least one rounded lobe and coupled to one of said pistons for rotation therewith; a second toothed gear having at least one rounded lobe and engaged with said first gear for the rotation of said first gear in response to the rotation of said second gear; a third toothed gear; means to couple said third gear to said second gear for rotation in unison about the same axis; a fourth toothed gear coupled to the other of said pistons for rotation therewith, with said fourth gear being engaged with said third gear-for rotation in response to the rotation of said third gear; the engagement between said second gear and said first gear being indirect and being provided by an intermediate toothed gear between said first gear and said second gear; and the engagement between said third gear and said fourth gear being indirect, being provided by another toothed intermediate gear between said third gear and said fourth gear and which is meshed with said third gear and said fourth gear.

12; In a rotary engine having a housing defining a circular chamber, and at least two pistons joumaled within said circular chamber about the axis thereof for rotation and relative angular reciprocation about said axis, means to regulate rotation and relative angular reciprocation of said pistons, said means comprising:

A toothed internal first gear which is internally oval and is coupled to one of said pistons for rotation therewith; a toothed second gear having at least one rounded lobe and which is engaged with said first gear by direct mesh; a toothed third gear, coupled to said second gear; a toothed fourth gear coupled to another of said pistons for rotation therewith, with said third gear and said fourth gear being engaged by direct mesh, the gears co-operating to cause at least two of said pistons to undergo relative angular reciprocation and rotation.

13. In a rotary engine, a housing defining a circular chamber, at least two pistons journaled on the axis of said circular chamber for rotation and for angular reciprocation of at least one piston relative to another about said axis, and means to regulate rotation and relative angular reciprocation of said pistons, said means comprising:

An internal first gear which is internally oval and is coupled to one of said pistons for rotation therewith; a second gear having at least one rounded lobe and which is engaged with said first gear; a third gear coupled to said second gear; a fourth gear coupled to another of said pistons for rotation therewith, said fourth gear being directly engaged with said third gear, the gears co-operating to cause at least one of said pistons to undergo rotation relative to said housing and angular reciprocation relative to another of said pistons. i 

1. In a rotary engine, a housing defining a circular chamber, two radial pistons journaled on the axis of said circular chamber for rotation and relative angular reciprocation, each piston comprising at least one curved segmental block, at least two of said segmental blocks being arcuate, said pistons and said circular chamber defining at least two working chambers that successively enlarge and decrease in volume upon relative angular reciprocation of said pistons, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising, A first gear characterized by two rounded lobes and coupled to one of said pistons for rotation therewith; a second gear characterized by N rounded lobes, N 1,3 or any interger number greater than 3, said second gear engaged with said first gear; a third gear characterized by having the same number N of rounded lobes as said second gear, said third gear coupled to said second gear for rotation therewith about an axis stable relative to said housing; a fourth gear characterized by two rounded lobes and engaged with said third gear and coupled to the other of said pistons for rotation therewith.
 2. An invention according to claim 1, with each piston comprising two remote curved arcuate segmental blocks, with each curved block generally triangular and bounded by generally radial faces, means to rigidly interconnect the curved blocks of one said piston, means to rigidly interconnect the curved blocks of the other said piston, each of the said pistons having central bosses extending part way into said circular chamber, the two pistons interfitting with one another within said housing with the said central bosses side by side adjacent to one another, said pistons and said circular chamber defining at least four working chambers that successively enlarge and decrease in volume upon relative angular reciprocation of said pistons.
 3. An invention according to claim 1 wherein said circular chamber is the generatrix of a body having all sides straight.
 4. An invention according to claim 3, said circular chamber being cylindrical, each piston comprising at least two said segmental blocks, and wherein said pistons and said circular chamber define at least four working chambers that successively enlarge and decrease in volume upon relative angular reciprocation of said pistons.
 5. An invention according to claim 1, with all the gears of said engine being disposed on one side of said housing.
 6. An invention according to claim 5, with means to couple said fourth gear to said piston comprising a drive shaft, the means to couple said first gear to the other said piston including a member circumvented over the said drive shaft.
 7. In a rotary engine, a housing defining a generally circular chamber, at least two pistons journaled on the axis of said circular chamber for rotation and relative angular reciprocation, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising, A first gear characterized by two rounded lobes and coupled to one of said pistons for rotation therewith; a second gear Characterized by one one rounded lobe and engaged with said first gear; a third gear characterized by one rounded lobe, said second gear coupled to said third gear; a fourth gear characterized by two rounded lobes and engaged with said third gear and coupled to the other said piston for rotation therewith.
 8. In a rotary engine, a housing defining a generally circular chamber, at least two pistons journaled on the axis of said circular chamber for rotation and angular reciprocation of at least one piston relative to another, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising, A first gear characterized by two rounded lobes and coupled to one of said pistons for rotation therewith; a second gear characterized by having N rounded lobes, N 1,3 or any integer number greater than 3, said second gear engaged with said first gear; a third gear, substantially circular, and coupled to said second gear; a fourth gear, substantially circular, and coupled to another of said pistons for rotation therewith and engaged with said third gear, the ratio of said third gear to said fourth gear being N:2.
 9. In a rotary engine, a housing defining a generally circular chamber, at least two pistons journaled on the axis of said circular chamber for rotation and angular reciprocation of at least one piston relative to another, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising, A first toothed gear characterized by having at least one rounded lobe, said first gear coupled to one of said pistons for rotation therewith; a second lobate toothed gear, said second gear being an internal gear, said second gear engaged with said first gear; a third gear, said third gear coupled to said second gear; a fourth gear coupled to another of said pistons for rotation therewith; means for direct or indirect engagement of said third gear with said fourth gear.
 10. An invention according to claim 9 wherein said first gear is characterized by two rounded lobes.
 11. In a rotary engine, a housing defining a circular chamber, two radial pistons, each piston comprising at least one curved block, with said radial pistons journaled within said circular chamber on the axis thereof for rotation and relative angular reciprocation about said axis, said radial pistons substantially defining within said circular chamber at least one working chamber that successively enlarges and decreases in volume upon relative angular reciprocation of said pistons and consequent approach and departure of said curved blocks, and means to regulate the rotation and relative angular reciprocation of said pistons, said means comprising, A first toothed gear having at least one rounded lobe and coupled to one of said pistons for rotation therewith; a second toothed gear having at least one rounded lobe and engaged with said first gear for the rotation of said first gear in response to the rotation of said second gear; a third toothed gear; means to couple said third gear to said second gear for rotation in unison about the same axis; a fourth toothed gear coupled to the other of said pistons for rotation therewith, with said fourth gear being engaged with said third gear for rotation in response to the rotation of said third gear; the engagement between said second gear and said first gear being indirect and being provided by an intermediate toothed gear between said first gear and said second gear; and the engagement between said third gear and said fourth gear being indirect, being provided by another toothed intermediate gear between said third gear and said fourth gear and which is meshed with said third gear and said fourth gear.
 12. In a rotary engine having a housing defining a circular chamber, and at least two pistons journaled within said circular chamber about the axis thereof for rotation and relative angular reciprocation about said axis, means to regulate rotatIon and relative angular reciprocation of said pistons, said means comprising: A toothed internal first gear which is internally oval and is coupled to one of said pistons for rotation therewith; a toothed second gear having at least one rounded lobe and which is engaged with said first gear by direct mesh; a toothed third gear, coupled to said second gear; a toothed fourth gear coupled to another of said pistons for rotation therewith, with said third gear and said fourth gear being engaged by direct mesh, the gears co-operating to cause at least two of said pistons to undergo relative angular reciprocation and rotation.
 13. In a rotary engine, a housing defining a circular chamber, at least two pistons journaled on the axis of said circular chamber for rotation and for angular reciprocation of at least one piston relative to another about said axis, and means to regulate rotation and relative angular reciprocation of said pistons, said means comprising: An internal first gear which is internally oval and is coupled to one of said pistons for rotation therewith; a second gear having at least one rounded lobe and which is engaged with said first gear; a third gear coupled to said second gear; a fourth gear coupled to another of said pistons for rotation therewith, said fourth gear being directly engaged with said third gear, the gears co-operating to cause at least one of said pistons to undergo rotation relative to said housing and angular reciprocation relative to another of said pistons. 